US3768432A - Shallow water adaptor for outboard motors - Google Patents

Abstract

A member adapted for coaction and operative association with an outboard motor and more specifically, the cavitation plate thereof whereby the boat with which the outboard motor is used may be operated in shallow bodies of water by the expedient of being able to aspirate ambient water to permit placement of the propeller of the outboard motor at a selected one of a plurality of positions wherein the propeller is capable of being positioned at various points with respect to the bottom of the boat so that in the normal state, the propeller is not fully positioned below the bottom of the boat. However, upon starting the outboard motor and turning on the propeller, water is aspirated to fully immerse the propeller and permit it to work against the aspirated flow of water to drive the boat through the shallow water even though part or all of the propeller may be located above the water surface generated by the hull bottom at planing speed.

Description

United States Patent 1191 Spaulding 1 Oct. 30, 1973 SHALLOW WATER ADAPTOR FOR OUTBOARD MOTORS [76] Inventor: Edward H. Spaulding, 4445 S.

Harbor Blvd., Oxnard, Calif.

[22] Filed: Oct. 18, 1971 [21] Appl. No.: 190,063

52 US. Cl 115 42, 115/12 A, 115/18 R 51 1111.01 B63h 5/06 [58] Field of Search 115/42, 18 R, 18 A,

[56] References Cited UNITED STATES PATENTS 7/l963 Montague l1S/42 6/1968 Hall ..1l5/12A Primary Examiner-Milton Buchler Assistant Examiner-Stuart M. Goldstein Attorney-Thomas P. Mahoney et al.

[5 7] ABSTRACT A member adapted for coaction and operative association with an outboard motor and more specifically, the cavitation plate thereof whereby the boat with which the outboard motor is used may be operated in shallow bodies of water by the expedient of being able to aspirate ambient water to permit placement of the propeller of the outboard motor at a selected one of a plurality of positions wherein the propeller is capable of being positioned at various points with respect to the bottom of the boat so that in the normal state, the propeller is not fully positioned below the bottom of the boat. However, upon starting the outboard motor and turning on the propeller, water is aspirated to fully immerse the propeller and permit it to work against the aspirated flow of water to drive the boat through the shallow water even though part or all of the propeller may be located above the water surface generated by the hull bottom at planing speed.

7 Claims, 9 Drawing Figures SI-IALLOW WATER ADAPTOR FOR OUTBOARD MOTORS BACKGROUND IF THE INVENTION There are many geographical areas throughout the world and more specifically, within the United States of America offering unique recreational areas that are prime vacation attractions for the outdoor camper, sports man and the like wherein a usual part of their gear is flat-bottom glat-bottom boat or the like for use with an outboard motor. Some regions for example, the Klamath River in Northern California have riffles consisting of swift shallow water where special caution must be exercised to avoid contact with the river bottom and the resultant damage to both motor and propeller.

A normal outboard motor is designed to operate with the propeller entirely below a plane defined by the aft extension of the bottom of the boat. This placement puts the propeller in its most effective position for propulsion and avoids the adverse effects of cavitation. The usual propeller placement, as for example with a 9.8 HP Mercury, extends at least inches below the bottom of the boat with which the outboard motor is used. At planing speed, the boat requires a clearance of 10 inches for the propeller plus about 5 inches to support the boat thus requiring a total depth of Water of inches for the propeller to just clear the river bottom or bed of other bodies of water on which the boat and outboard motor are utilized.

Engine and propellers have been damaged by a single rock lying on the bottom which encroaches upon the minimum depth, of for example 15 inches, within which a boat and motor can properly and safely operate. The prior art has suggested several solutions to the problem of permitting powered boats to navigate in very shallow water.

For example, the use of the conventional air propeller mounted on a flat bottomed sled or other vehicle is generally known for its extensive use in marsh like environments and especially, in the Florida Everglades. Other prior art devices comprise the use of a water jet drive adapted for use with an outboard motor and such jet drives are in use today on shallow rivers and the like bodies of water. Another alternative for navigation, with respect to shallow bodies of water, is the ground effect machine riding on a cushion of air. Tunnel boats are also prior art vehicles that permit navigation in very shallow waters.

However, most of these prior art devices are not susceptible to general sports use because of the cost involved; the highly specialized and sophisticated apparatuses, and similar such drawbacks which the present invention alleviates. In one instance, the invention pertains to a shallow water adapter for use with outboard motors which is easily connected to the cavitation plate of the motor and acts as a duct to guide water to the propeller so that it can work thereon to produce thrust. In the conventional outboard motor, if the propeller is raised so that its center line is tangent to the bottom of the boat or higher without the use of the invention, the propeller will cavitate and produce little or no thrust. However, through the use of the. invention, the entry of air into proximity to the propeller is prevented and atmospheric pressure forces surrounding water to fill the duct which then guides the water through a curvilinear path toward the propeller where thrust is produced.

Obviously, other embodiments are contemplated wherein the device of the invention is made integrally with an outboard motor as an original piece of equipment, the motor then being specialized for shallow water usage. Inboard motors are also contemplated.

OBJECTS AND SUMMARY OF THE INVENTION It is an object of the invention to provide a means for a boat motor to allow use thereof in shallow water.

It is another object of the invention to provides means for and a method whereby a motor having a propeller may be used effeciently in conjunction with a boat in a shallow body of water.

It is still another important object of the invention to provide a device which is utilizable with an outboard motor to permit the boat with which the outboard motor is used to be utilized in shallow water whereby the propeller is not or only partly placed below the bottom of the boat.

It is still another and more specific object of the invention to provide an adapter for operative association with an outboard motor and more specifically, the cavitation plate thereof to allow the propeller of the motor to normally be positioned above orpartly above the bottom of the board and still be able to effectively propel the boat through shallow water.

It is still another and even more specific object of the invention to provide means for cooperation with a power boat whereby the power boat may be operated in shallow water wherein ambient water is aspirated to the propeller to permit propelling of the boat through the said shallow water.

It is still an even further and more specific object of the invention to provide means for association with the cavitation plate of an outboard motor whereby water may be aspirated to provide a working medium against which the propeller may work to propel a boat through shallow water.

It is still another object of the invention to provide an adapter of molded fiberglass plastic or formed metal which acts as a duct to aspirate water from forward of the propeller to aft thereof to permit use and effective operation in shallow water.

It is another object of the invention to provide a method of operating power boats in shallow water wherein ambient water is moved through a curvilinear path from forward of the propeller of the motor to a point aft thereof wherein the ambient water is aspirated through the flow path.

Generally, in exemplary embodiment the invention is' directed to a means for a motor mounted on a boat to permit operation in shallow water comprising the combination of a member adapted to be in at least partial encircling relationship to the propeller of said motor and having walls defining an inlet end adjacent one side of said propeller and being of relatively low profile to receive water and have rearwardly directed walls defining an outlet end of higher profile adjacent said other side of said propeller to effect a directed aspirated flow of water from said inlet end toward said outlet end. A method of operating boats utilizing an aspiration function is also involved.

, These and other objects of the invention will become apparent from the drawing and the hereinafter following commentary.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an elevational view of one embodiment of the invention illustrating its use in conjunction with a typical outboard motor;

FIG. 2 is a view taking along the line 2--2 of FIG. 1;

FIG. 3 is a view taken along the line 33 of FIG. 1;

FIG. 4 illustrates another embodiment of the invention showing the outboard motor and more specifically, the propeller thereof in an even more upraised position with respect to the transom of the boat with which it is associated;

FIG. 5 is a view taken along the line 5-5 of FIG. 4;

FIG. 6 shows still another embodiment of the invention and shows the propeller raised the same as in FIG. 4 but incorporating a circular exit, to allow use of stator vanes to improve flow and efficiency.

FIG. 7 is a view taken along the line 7-7 of FIG. 6;

FIG. 8 is a fragmented view taken along the line 8-8 of FIG. 7; and

FIG. 9 is a bottom view of the embodiment illustrated in FIG. 6 taken along the line 99 thereof.

DESCRIPTION OF THE BEST EMBODIMENTS CONTEMPLATED Referring to the figures of drawing wherein like numerals of reference designate like elements throughout and specifically, referring to FIGS. 1-3 inclusive an exemplary embodiment of the invention is illustrated wherein the member 2 is of duct or inverted scoop-like configuration having an inlet end 4 and an outlet end 6.

It will be noted that the member 2 is in at least partial encircling and overlying relationship with respect to propeller 8 of outboard motor 10 shown in phantom line mounted on the transom or extension thereof 12 of flat bottom boat 14.

In this instance, outboard motor 10 is provided with cavitation plate 16 by which means the member 2 may be secured thereto as will be described.

The member 2 has an inlet end 4 having a depending lip portion 18 of relatively low profile forming an inlet of sorts as will become apparent. The walls of the member 2 are upwardly directed with respect to the lip 18 in curvilinear fashion as illustrated terminating in the rear edge 20 aft of propeller 8. The upper or top wall 22 of member 2 is slotted as at 24 so as to accommodate the shaft housing 26 in close fitting engagement. Upper wall 22 therefore, is provided with spaced apertures 28 to receive through bolts 30 for rigid securement of member 2 to cavitation plate 16.

In the FIG. 1 embodiment, the motor 10 is selectively positioned to operate in relatively shallow water with the propeller 8 being only about half extended below the boat bottom. It will be noted that a transom extension or board 12 is secured to the stern of the boat to allow for this upward positioning of the motor 10 with respect to the bottom of the boat 14. In this condition, the center line of the propeller is approximately tangent to the bottom of the boat 14 (FIG. 2).

The inlet end 4 and more specifically, the lip 18 depends or extends less than about an inch below the bottom of the boat 14 and is of nearly rectangular crosssection with an open bottom, as best seen in FIG. 3. This positioning is such that only water is allowed to enter the forward or inlet end of the member 2. So as to facilitate air exclusion, the bottom of the boat 14 adjacent the lip 18 is preferably substantially flat with a planar surface as opposed to one having ridges protuberances or the like. If these are present on the bottom of boat 14, the member 2, as well as the motor 10, must be lowered for full efficiency so that the lip 18 will be below the lowest projection of the bottom of the boat 14.

In this particular instance, the member 2 is of molded fiberglass or metal construction and has upwardly extending curvilinear walls forming a flow path from the inlet end to the outlet end for water which is aspirated not only through the entry defined by lip 18 but by the outer boundaries of the side walls 32 of member 2. It will be noted that the upper extremity or edge 34 may extend beyond the lower edge 36 so as to facilitate water flow through the curvilinear path defined by the walls of member 2.

It is important in the efficient operation of an outboard motor utilizing the member 2 (for fullest efficiency) to exclude air entry into the curvilinear path of water flow and to this end, the walls 32 depend or extend about 1 inch below the plane determined by the bottom of the boat 14 and consequently the axis of the propeller 8.

In operation of the outboard motor 10 with the member 2 secured in place as shown in FIG. 1, the water flow through the curvilinear path defined by member 2 will be established when the boat 14 is at rest with the stern thereof depressed so that the member 2 is submerged in dead water. The turning of the propeller 8 will start water flow through member 2; the velocity of which will increase as the motor speed increases and hence, the speed of the boat. Once flow is established, which is essentially smooth and continuous, (the supply being taken from the ambient water with which the device is used) all air will be excluded from entering into the confines of the member 2. Since the member 2 does not permit air entry, atmospheric pressure or an aspirating affect will force ambient water upwards into the member 2 from the inlet end 4 toward the outlet end 6 furnishing a body of water at the ,propeller 8 against which it may work in order to propel the boat 14 in conventional fashion.

It will thus be seen that with the embodiment of the invention depicted in FIGS. 1, 2 and 3, that the propeller 8 is raised to where its center line is roughly tangent to the bottom of the boat 14, more specifically, raised a distance one-half of its diameter plus the normal amount of submergence required to make it operate with the cavitation plate 16. This allows the boat to operate in much shallower water than before and would be satisfactory for all but the most shallow water situation. Water is raised only in moderate amounts thus keeping down the wetted area of the member 2 and keeping the efficiency of operation of the motor 10 at a relatively high level although some efficiency is sacrificed. In practice it will be found that the device 2 is most efficient when the inlet lip 18 is positioned slightly forward of the transom and directly below the boat stern. This placement is easily determined and accomplished by the normal pivotal positioning provided by the usual outboard motor mounting bracket in achieving best planing position.

Referring now to FIGS. 4 and 5, another embodiment of the invention is illustrated. Herein the member 42 is similarly positioned with respect to an outboard motor 10 but in an upward position with respect to a transom or transom extension member 12 such that the propeller 8 is completely raised above the plane of the bottom of the boat 14. In this position, it is possible to operate and propel the boat 14 in any body of shallow water capable of floating the boat 14.

In this instance, the member 42 has an inlet portion 44 and an outlet 46 much the same as the member 2 previously described. Note that the motor has been pivoted to position the inlet 44 below the bottom of boat 14 as earlier described. However, while the inlet end 44 is of low profile as in the member 2, it will be noted that the walls of the member 42 curve and extend upwardly in accentuated configuration as compared to the 'member 2 earlier described. The reason for the increased slope as at 48 is solely to provide a curvilinear path for water entering into the member 42 so that it is guided toward propeller 8 in sufficient amount to allow the well known action and reaction resultant so that the motor 10 and more specifically, propeller 8 may propel boat 14.

Because the propeller 8 is totally above the bottom of the boat 14, the side walls 50 and 52 extend and depend a greater distance than the walls 32 of member 2..

It will be noted that the depending length of walls 50 and 52 are such so as to exclude the presence of passage of air into the confines of the chamber or duct formed by member 42.

As in the case with member 2, member 42 is secured to cavitation plate 16 by means of through bolts provided for that purpose. To improve proper water flow through the member 42, an optional, demountable, upward rear extension 54 may be provided for securement to member 42 by means of riveting or through bolts which is in flush engagement with the interior wall of member 42 and preferably the exterior wall also. The extension 54 while shown as a separate, nonintegral part may be fashioned integrally with the remainder of member 42 for permanent installations. While the interior surface of the attachment 54 is shown as being flush with the interior wall member 42, it may not necessarily be thus and in some instances this interior surface may be shaped and configured to direct exit water slightly downward toward the axis of the propeller 8 to help control trim of the boat 14 when underway. I

Referring now to FIGS 6, 7, 8 and 9, still another embodiment of the invention is illustrated. Member 62 has the same profile previously described for member 42. The main difference is the inclusion of a circular exit which improves propeller efficiency by reducing tip vortex losses. It also allows the addition of exit stator blades to straighten out the circular flow from the propeller and further increases efficiency.

As before, the member 62 is provided with mounting slot 70 for cooperation with the shaft housing and association with the cavitation plate 16 or motor 10. It will be noted that the lower portion of the motor 10, and specifically the propeller 8, has not been shown in FIG. 9 for purposes of clarity.

Again, in this instance, the depending side walls 72 and 74 are such as to exclude and inhibit the passage I of air into the duct or chamber formed by member 62. In this embodiment, an outlet end member 76 which is separately securable to member 62 by appropriate means, such as through bolts and the like, has the upper edge overlapping portion 78 to direct fluid flow from the curvilinear path determined by member 62 and can be provided with a series of spaced vanes or fins 80 emanating in ray form from a central portion 82. The vanes or fins act much like stator turbine blades to straighten out the circular flow of water driven off the propeller to thereby increase thrust efficiency of motor 10 and more specifically propeller 8. Improved propeller efficiency may also be expected with the circular exit even without the addition of stator vanes shown in the FIG. 6 embodiment.

In the embodiments shown in FIGS. 4 and 6, the propeller is completely raised above the plane of the bottom of the boat. The efficiency of these two embodiments is somewhat less than that obtained from the FIG. 1 embodiment due to the greater wetted area and the increased height through which water must be raised in order to propel the boat through the shallow body of water in which the boat 14 is used. In each of the latter two embodiments, it is more difficult to back the boat when the motor 10 is in reverse gear because of the fact that the propeller is so near the surface of the water. It is contemplated that reversing clam shell doors can be provided similar to those used to reverse thrust on aircraft jet engines when thrust reversing is considered to be an important feature. In this case the propeller will only act in the forward direction and reversing will be had when the thrust-reversing doors are actuated.

While the addition of the shallow water adaptor member of the invention has reduced the ability of the boat to move backward in reverse gear, still in all, the configuration of the member as shown in FIG. 1 has the propeller 8 sufficiently submerged in water so that backing is sufficiently energetic to cover practical needs. The embodiments shown in FIGS. 4 and 6 since they involve having the propeller raised to a much greater extent than that shown in FIG. 1 only slight backing action is possible. But as earlier stated, an aircraft type thrust reverser can be fitted to provide backing ability as an optional extra.

While the invention has been described and specifically illustrated in conjunction with an outboard motor, such need not be the case as there are instances where inboard motors having a permanent structure keeping within the spirit of the disclosed invention will be possible. Additionally, while a conventional flat bottom or nearly flat bottom boat of the row-boat class has been used as an example, other classes of boats are also contemplated so long as the essence of the invention is maintained. Moreover, while fiberglass has been disclosed as a suitable moldable material from which to make the the shallow water adaptor, it is also contemplated that plastics or metals, particularly the light metals, will also suffice. Needless to say, there are instances where the adaptor of the invention will be made integral with the motor housing and secured thereto in a manner not requiring attachment to the cavitation plate. However, in the general case because of versatility of an outboard motor, it is desirable to have the devices of this invention be demountable so that the outboard motor with which they are associated may be used in normal or conventional waters of sufficient depth to allow effective usage.

Thus, in general and in specific detail there has been disclosed, devices for propelling a boat through shallow water in a highly effective manner. In the operation of the devices, the method involved, as is clearly discernable from the foregoing, comprises positioning the propeller of the motor in a selected one of a plurality of positions so that the propeller will clear the bottom or bed of a shallow body of water over which it is desired to propel a boat. Ambient water is aspirated from the surrounding body of shallow water to completely surround the propeller so as to provide a medium against which the propeller may work so as to set up the well known equal and opposite action-reaction thrust situation to propel the boat over the shallow body of water.

Certain modification in the devices and the method of utilizing them will at once make themselves apparent to those of ordinary skill in the art. For example, the configuration of the devices and specifically the inlets thereof, may be other geometric shapes than those shown. Likewise, weed bars and the like may be provided to prevent propellor fouling. All such changes, modifications and variances are intended to be covered by the appended claims.

I claim:

1. Means for an outboard motor adapted to be mounted on the transom of a boat to permit operation in shallow water comprising the combination: a member adapted to be in at least partial encircling relationship to the propeller of said motor and having walls defining an inlet end of rectangular cross-section positioned on either side of or within a plane determined by the bottom of said boat and being adjacent one side of said propeller and being of relatively low profile to receive water and having rearwardly directed curvilinear, upwardly sweeping with respect to said inlet, walls to promote smooth water flow and defining an outlet end at least semi-circular in cross-section of higher profile and being adjacent the other side of said propeller to effect a directed, aspirated flow of water from said inlet end toward said outlet end, said walls defining said inlet end and said outlet end presenting an upper closed path through which said water is directed, and the upper extremity of said outlet end projects beyond the lower extremity of said outlet end.

2. The member is accordance with claim 1 wherein at least the outlet portion rearward of said propeller is provided with means to effect smooth. non-turbulent flow of water therethrough.

3. The member in accordance with claim 2 wherein said means comprises fins or vanes on the interior wall of said outlet end portion. I

4. The member in accordance with claim 3 wherein said outlet portion having said fins or vanes is separately demountable from the remainder of said member.

5. The member in accordance with claim 1 wherein it is adapted for securement to the cavitation plate of said outboard motor.

6. The member in accordance with claim 5 wherein the upper wall thereof is slotted to permit snug fitting engagement of said outboard motor shaft housing.

7. The member in accordance with claim 6 wherein the material of construction is moldable fiber glass and said member is bolted to said cavitation plate and the transom of said boat is upwardly extended to receive said outboard motor at one of a plurality of positions wherein said propeller is variously positioned with respect to the water surface.

Claims (7)

1. Means for an outboard motor adapted to be mounted on the transom of a boat to permit operation in shallow water comprising the combination: a member adapted to be in at least partial encircling relationship to the propeller of said motor and having walls defining an inlet end of rectangular cross-section positioned on either side of or within a plane determined by the bottom of said boat and being adjacent one side of said propeller and being of relatively low profile to receive water and having rearwardly directed curvilinear, upwardly sweeping with respect to said inlet, walls to promote smooth water flow and defining an outlet end at least semi-circular in cross-section of higher profile and being adjacent the other side of said propeller to effect a directed, aspirated flow of water from said inlet end toward said outlet end, said walls defining said inlet end and said outlet end presenting an upper closed path through which said water is directed, and the upper extremity of said outlet end projects beyond the lower extremity of said outlet end.

2. The member is accordance with claim 1 wherein at least the outlet portion rearward of said propeller is provided with means to effect smooth, non-turbulent flow Of water therethrough.

3. The member in accordance with claim 2 wherein said means comprises fins or vanes on the interior wall of said outlet end portion.

4. The member in accordance with claim 3 wherein said outlet portion having said fins or vanes is separately demountable from the remainder of said member.

5. The member in accordance with claim 1 wherein it is adapted for securement to the cavitation plate of said outboard motor.

6. The member in accordance with claim 5 wherein the upper wall thereof is slotted to permit snug fitting engagement of said outboard motor shaft housing.

7. The member in accordance with claim 6 wherein the material of construction is moldable fiber glass and said member is bolted to said cavitation plate and the transom of said boat is upwardly extended to receive said outboard motor at one of a plurality of positions wherein said propeller is variously positioned with respect to the water surface.

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